# [ntp:questions] how long does it take ntpd to sync up

unruh unruh at wormhole.physics.ubc.ca
Sun Aug 28 05:42:53 UTC 2011

```On 2011-08-28, Harlan Stenn <stenn at ntp.org> wrote:
> Bill wrote:
>> On 2011-08-27, Harlan Stenn <stenn at ntp.org> wrote:
>>> Bill wrote:
>>>> On 2011-08-27, Chris Albertson <albertson.chris at gmail.com> wrote:
>>>>> Use some logic.  Assume you want to set a mechanical clock's speed
>>>>> by moving the "slow/fast" lever and you can see the time only to
>>>>> the nearest
>>>>
>>>> Ah yes, but why a) would you want to only adjust it that way, an b)
>>>> why not do a fit and figure outexactly what the rate of the clock is
>>>> and how far out it is, and correct that, rather then simply "shove
>>>> the rate a bit higher if you see the clock time is behind time now,
>>>> and a bit slower if you see the clock is ahead." (which is what ntp
>>>> does).
>>>
>>> Using phrases like "shove the rate a bit" seems pretty disingenuous
>>> to me, Bill.
>>
>> ?? Not sure what you mean? ntp works by altering the rate in order to
>> eliminate the offsets. Is it the infomality of "shove" you object to?
>
> ntp *does* a fit/figure of the expected needed adjustment - your
> sentence implies that it does not (at least that's how it reads to me).

ntpd, when it is running at least, simply does a feedback system-- if the
time offset on the current measurement is slow, the clock is slowed
down, and if it is fast it is speeded up and this happens at each poll